Electric clock



ELECTRIC CLOCK Filed May 10, 1930 3 Sheets-Sheet 1 "m i ffjfjfjjjjfmfenm Aug. 16, 1932. R. H. WILMETH ELECTRIC CLOCK Filed May 10. 1930 3Sheets-Sheet 2 Patented Aug. 16, 1932 i UNITED STATES PATENT OFFICEnoscon n. WILMETH, or srnmermtn, ILLINOIS, Assicmon TO SANGAMO ELECTRICCOMPANY, or SPRINGFIELD, rumors, A CORPORATION or rumors spring of theclock to act on ELECTRIC cLocx Application filed May 10, 1930. serialNo. 451,216.

The present invention relates to electric clocks, and particularly tovstriking, clocks adapted to strike at certain time periods, such as onthe hour, half hour, etc. i

Electric-clocks are now generally provid ed with an electricallyoperated means for operating the] striking mechanism. This provisionusually consists of the employment of an electric motorin addition tothe conventional winding motor, which is cont-inuously connected acrossthe current supply line. While this arrangement has an advantage in thatthe operation of the striking mechanism in no way affects the timingcharacteristics of the clock, there are nevertheless severalmajorobjections thereto. It will be apparent that in such-a construction, itthe current supply fails prior to a striking period, thestrikingmechanism mustnecessarily remain silent. must necessarily beemployed in such an arrangement, thus materially increasing themanufacturing costs of this type of striking clock. 1 t t i The presentinvention contemplates the em ployment of the winding motor to operatethe striking mechanism during a striking pe- 'riod, at the same timepermitting the main the striking mechanism toa slight degree.Thus,'should the current supply fail during a striking period, provisionis made for. carrying over of the operation of thestriking mechanism bythe main spring. These functionsare accomplished by the interposition ofa difler ential gear in the series of reduction gears between the mainspring and the winding motor. This differential gear is adapted totransmit power from the winding motor to g the striking mechanism duringa striking ffperiod without producing any winding e ect on the mainspring,which during a striking period is adapted to unwind. somewhat inspite of the operation of the winding motor. Thus, during a strikingperiod, all the energy transmitted to the clock mechanism by the windingmotor is absorbed by the striking mechanism. This is accomplished byjsoa'rranging the reduction gears that the maxirate at whichthe motor canwindthe mum Furthermore, two motors main spring is always somewhatlessthan the rate of-unwinding of the main spring during the strikingoperation, with the result that with the power either on or oil', themain spring is unwinding slightly during a striking period.

With the. above in view, the main object of this invention is to providea striking clock wherein the operating energy for the time keepingmechanism and for the striking mechanism is derived electrically, asfrom the ordinary house lighting circuit.

Another object is .to provide a striking mechanism operable by a windingmotor for the main spring or" by the main spring. A further object isthe provision of a novel gear'connection between the winding motor andthe main spring so that the main spring at all times acts to limit theamount of energy delivered by the motor to the strikin mechanism.

Anotlier object is, the provision of a novel gear connection between thewinding'motor and the main springso that all the energy delivered by thewinding motor is taken up by the striking mechanism during a strikingperiod." k p A further object is to provide such a gear arrangementthat. the striking mechanism the winding motoris operating. 1

A further object is the provision of a novel gear arrangementwhereby'the maximumspeed at which the motor canwind the main spring isalways somewhat less'than the rate or unwinding of the main springduring a striking operation.

Another object is to providea novel striking means whereby clearlydistinguishable audible signals are emitted at predetermined timeperiods such, for example, as hourly ,3

and half-hourly periods by the operationof a single operating mechanism.This is accomplished. by the provision of two coacting striking hammerarms having a lost motion provision therebetween whereby both arms maybe actuated in unison or one of them without the other. Thus at the hourinterval, two gongs are struck while on the halfhour only one is struclIn conjunction with this port-ion of the mechanism, a control means hasbeen provided for rendering one of the arms ineffective at the half-hourpcriod.

Other and further objects will appear from the following detaileddescription of an embodiment of my invention illustrated theaccompanying drawings in which;

Figure l is a fragmentary elevational view of a clock, portions thereofbeing broken away to illustrate the striking mechanism control elementsFigure 2 is elevationa-l section of the clock frame behind the frontframe plate, and showing the r duction gears from the winding motor tothe main spring;

Figure 3' is a section similar to i M, taken along a plane closer to therear frame plate and. illustrating the striking mechanism;

Figure is a transverse section of the clock mechanism taken along theline 4-4 of Figure 2;

Figure 5 is transverse section of the striking mechanism taken along theline 55 Figure 3 and showing the differential gear section;

Figure 6 is a detailed view of the differential gear; and

liigure is an enlarged perspective detail of the hammer arm mountsillustrating the lost motion provision therebetween.

The operating parts of the clock may be enclosed in a. housing of anypreferred design, with striker gongs 11 and 12 disposed either to oneside of or below the clock mech anism proper; The clock movement isassembled between the front and rea frame plates13 and 14, which areheld in spaced relation by intermediate spacing posts 15. An electricmotor mechanism 16 for winding the clock movement and for operating thestriker mechanism is preferably mounted on the rear side of the rearframe plate 14. This motor maybe of any type or construction capable ofremaining in a stalled position over indefinite time periods, and isdirectly connected across the line. Preferably, this motor is analternating current induction motor of the general constructiondisclosed. in the copending application of Frederick C. Holtz, SerialNo. 750,201, filed November 15, 1924.

I shall first describe the driving train of the clock to illustrate itscorrelation with the striking mechanism and the winding operation. Inthe exemplary construct-ion shown, the armature shaft 21 of the clockmotor 16 extends through the rear plate 14 of the frame and carries apinion 22 which meshes with a spur gear 23 on an arbor 24.

It will be understood that the gear train which I am about to describeis disposed between the spaced frame plates 13 and 14 and that theseveral arbors to which reference shall be made are journalled at theirfront and rear ends. in. these plates, respectively. Mounted on thearbor :24 isa pinion 25 which meshes with a large gear 26 on a secondarbor 27. This latter arbor carries a pinion 28 which. meshes with alarge gear 29 on a third arbor 31 towhich a pinion; 32. is secured. Thelatter pinion 32 meshes with a bull gear of aspur-gear differential,enerally indicated at 34.

Referring particularly to Figure 5, the differential 34 comprises thebull gear- 33 which carries thereon two diametrically disposeddifferential pinions 36 rotatably mounted on shafts 37 which have theirend portions cut away to form flat, diametric surfaces 38. The shafts 37are seated in recesses 39 with the fiat end surfaces in align ment withthe rear surface of the bull gear 33, and are retained in fixed positionthereon by bolts 41, theundersides of the heads of which engage the fiatend surfaces of the shaft 37- Each of the differential pinions 36 hasbearing portions 42 which extend beyond either of their faces and occupythe entire space between the gear periphery and the web portions 33thereof, with the toothed peripheries closer to the periphery of thebull gear 33 than to the hub thereof. A shaft 43 carries the bull gear33, which is rotatably mounted thereon.

Between. the front frame plate 13 and the front end of the hub of thebull gear, a spur gear 44 having a forwardly extending hub portion 45,is rotatably mounted on the shaft 43, the forward end of the hub 45bearing on the rear of the front frame plate 13, and the rear face ofthe gear 44 at the hub hearing on the forward end of the hub of the bullgear. The teeth of the spur gear 44 are meshed with both differentialpinions 36. Secured fixedly to the hub portion 45 of the gear 44 andforwardly of this gear, is a smaller spur gear 46. Rotatably mounted onthe shaft 43 between the rear plate 14 and hub 34 of the bull gear, is aspur gear 47. having a rearwardly extending hub portion 48. the rear endof which bears on the front face of the rear frame plate 14 while thefront face of the gear 47, at the hub bears on the rear end of the hubof the bull gear 33. The difierential pinions 36 mesh with the gear 47.The rearwardly extending hub portion 48 of the gear 47 carries thereon.and fixedly secured thereto, a larger spur gear 49, having a series ofrearwa-rdly extending circumferentially spaced pins 51. The purpose ofthese pins will be hereinafter described.

Referring now to Figures 2 and 4, the gear 46 meshes with a gear 52 onan arbor 53,'

the gear 52 in turn meshing with a gear 54 on an arbor 55 which carriesthemainsprmg end of the main. spring at 58. of the main spring issuitably connected with the main spring barrel 57, the cover 59 of whichextends radially beyond the edge thereof and is formed withcircumferential gear teeth 61. p

A collar 62 suitably splined or otherwise connected to, the arbor 55 inany suitable.

manner for rotary movement therewith and sliding movement therealong,has a threaded rear portion 63 which en ages internalthreads in a boss64 extending forwardlyv from the cover 59. The collar 62 has at itsforward end a radially extending flange 65, the rear face of which bearsagainst a fork 66 of a brake supporting lever 67 pivoted to a supportingpost 68 secured to the forward frame plate 13, at 69. The brakesupporting lever 67 is normally spring projected forwardly by a flatspring 71 suitably secured thereto at 72 with its free end abutting therear end of the post 68. A brak'e 73 is adjustably secured to the lever67 at- 7 4 and carries thereon a brake shoe 75 which is adapted toengage the forward face of the gear 23 as the main spring approachesits.

fully wound condition to brake the operation of the winding motor 16 andto stop the latterwhen the main spring is in fully wound condition. i jc A pinion7 6 on a cannon pinion arbor 77 meshes with the gear on themain" spring cover plate 59 and transmits motion to-the arbor 77 towhich, near the forward end thereof and behind the front frame plate 13,a gear 78 is secured. The latter gear meshes with a pinion 79 onan arbor81 to. which a gear 82 is also secured and which transmits rotarymovement to a pinion (not shown) on an arbor 83. The latter arborhassecured thereon a gear 84 which meshes with apinion 85 of anescapement mechanism 86; The mechanism thus far described completes thetrain of gearingleading from the winding motor to the main spring and tothe escapement mechanism.

Referring now particularly to Figures 3 and 5, the gearing arrangementfor the strik-v ing mechanism comprises a pinion 91 on an arbor 92 whichmeshes with the gear 49'of the differential 34. A large gear 93 fixed tothe arbor 92 meshes with a'pinion 94 on an arbor 95 which carries a gear96 meshing with a pinion 97 on an arbor 98. The latter arbor carriesthereon a vane type, air beat-er governor 99. The arbor 95 carriesthereon and secured thereto, a stop arm 101 adjacent the gear 96'andwhich is adapted to rotate 7 in a, plane between the gear 93 and theforward edge of the governor 99, so that it is positioned proximately tothe forward frame plate 13. The gear 93 is provided with a forwardlyprojecting pin 102 near its periphery and which projects into a circulargroove103 provided on the rear side of the ront frame plate 13. The freeend of pin 102 is spaced from the side and bottom walls of the groove103 and its path is circular about the arbor 92. Thelatter arbor hassecured thereto on its forward end, which projectsthrough the frontframe plate 13, a cylindrical head member 104 which carries aforwardlyprojecting pin 105 thereon, eccentrically mounted with respectto the arbor 92. The purposes of the pins 102 and 105 will behereinafter explained.

An arbor 106 mounted adjacent. the periphery of the frame plates 13 and14, and bull gear33, carries thereon a dog 107 having a shoulder 108,against which one end of the flat spring109 bears with the other endseated in arecess (not shown) in the rear frame plate 14.

The projected end of the dog 107 engages the teeth of the bull gear 33preventing its rota t" on in unwinding direction while permittingrotationthereof in winding direc- 'tion.

The rear frame plate 14 has a radial outwardly extending integralprojection 111 thereon, in proximity to the differential 34;

A stop or dog member 112 is pivoted to the front face of the rear frameplate 14at a point 113 spaced radially and inwardly of the projection111. This stop member coniprises a bell crank having an arm 114 whichhas a perpendicular forwardly extending projection 115, and a laterallyextending arm 116 having a T-shaped head portion 117 whichhas rearwardlybent arms 118 and laterally extending projections 119. The forrear frameplate 14, are adapted to abut the radial edge'sof the projection 111 tostop the stop member 112 in its operative and inoperative positions; Theprojections 119 extend beyond the outer edge of the projection 111 andcan be easily gripped by the fingers of an operator to move the stopmember 112 about its pivot 113 to operative or inoperative position. henswung to operative position,

upon engagement of the stop portion 115 with any of the pins 51, thestriking mechanism is made inoperative when so desired.

Referringnow more particularly to Figures 2, 3 and 7, the audible signalproducing means comprises a pair of bell striking ham- 3 mer arms 121and 122, the actuation of the two in unison constituting the hour strikeand arm 122 being actuated alone to constitutethe ter ing lug at itsfree end.

arcuateportions 129 and 111 are ecce half-hour strike At their outerends, arms adapted to be ra'sed and dropped upon gongs 12 and 11 repectively. The intermediate portion of arm 122 is reversely bent to forma U-sha led portion 123 which is suitably seated wi an arm 12 1-suitably secured to an arbor journaled in the front and rear frameplates adjacentthe differential 33 in proximityto the peripheries of theframe plates, arm 121 being disposed adjacent rear frame plate 11 andhaving a portion 126 adapted to be disposed normally in the path ofmovement of pii 1 or gear 49. The inner end of arm is rormed into anarcnatc portion 129. the purpose of which wi 1- hereinafter described.Arm 121 is like provided with reversei x bent U-shapetl po tion 131Figure 2) the legs of which are embraced by two rolled care 132 formedfrom laterally projecting lugs extending from one leg. 133 ofa U-shapelsupportin member 131. This member mounted for pix al movemen about arbor127 with leg 3; abutment with the front face of arm 12" other leg 135being disposed in pro. 1 the rear face of the fro. frame plate 1 Leg 133also provided with a later-ah; l ng lug 136 having a rearwardlv bent endportion 137, one edge of which is adapted to normally abut the adjacentedge of arm 12 1-. Leg 135'is provided with right -zmgularly extendingarm 138 having a forwardly extenrh This lug 139 er tends forwardlythrough an arcuate slot 186 in the front frame plate 13 and for a shortdistance beyond the front face of said frame plate (see Figure 1). Thepurpos of arm 13S and lug 139 will be hereinafter described. The innerend of arm 121 is also pro ded with an arcuate portion 141. Rolled s 112extendinglaterally from leg 135 are provided for alternate positioningof arm 121. The trica ly disposed with respect to arbor 127 and in theinoperative positions of arms 121 and 122 are dis ,osed in the sameJlane. It will be now apparent that-s nce member is freely rotatable onarbor 127 while arm 121 secured to the arbor. and further since lug 13.71 merely abutting engagement with arm when arm 121 is cammed downwardlyby pins 51. both arms 121 and 122 are e ev ted in uni- As each pinreleases arm 1' in pa ssing, both arms 121. and 122 are grai it actuateddownwardly by the weight bf hammers and 126, strikingbells 11 and 12 atthe bot tom of each stroke. The operation of gen" 19 carrying pins 51 isso controlled to stop the gear with one pin 51 in engagement with theupper edge of arm 121- a. el 11 i inafter -described in conjunction withthe detailed description of the operation of the clock and controlmechanism. To prevent arms 121 and 122 from descending farther thanisrequired to give an audiblesignal by strikingthe gongs 11 and '12, andto further limit the downward movement thereof in arcuate'portions 129and 141 of arms 12-1 and" I shall now describe the control mechanism forthe striking mechanism, reference being had particularly to Figures 1ands.

It will be understood that the control mechanism is positioned on thefront face of the frame plate 13 between this plate and the dial, withonly those parts projecting through the front frame plate as will be soindicated. Pivotally supported on the outer face of the front frameplate 13 are three levers 151, 161 and 171 pivoted at 152,

162 and 172 respectively.

Lever 151 ha." a downwardly extending arm portion having an extension153 which carries a pivoted spring projected arm 154. The extreme end ofthe lever 151 has a stop projection 159 against which a lug 155 of thearm is adapted to abut in projected position. Intermediatethe ends oflever 151, a perpendicular rearwardly extending stop lug 156 isprovided. This lug extends through a slot- 157 in the front frame plate13 and is adapted to be moved into the path of a.

stop arm 101 against the pressure of a spring 181. The lug 156 is spacedfrom the arm 151 to form a recess seat 158 for a purpose to behereinafter described.

Lever 161, pivoted at 162, extends downwardly and at its free end isprovided with an arcuate toothed sector or rack 163, so that the leveris generally L-shaped. Intermediate the ends of lever 161, a finger 164is pivoted at 165 and is normally spring projected through the action ofa spring 167 against a stop lug 166 projecting forwardly from the lever161, so that it can be temporarily moved downwardly out of the path ofthe high point of a cam 182 in each rotation of the latter. Adjacent thepivot 162, the lever 161 is provi *d with a rearwardly projecting lug168; Spring 167 is coiled about the pivot 162 with one end thereofabutting the lower edge of the lug 168 and the other extending through arecess in a rearwardly projecting lug 169 on the finger 164. The teethof the rack 163 projeoct into the path of movement of the pin 1 5.

Spring 181is coiled about the oivot 151 with one end abutting the upperedge of the lug 168 and the other passing through a recess in the lug155, with the intermediate. portion thereof passing under the lug 156through the recess seat 157 and-is offset shipping of movementsindependently of 'the Lil-J side of the pivot and at its other end, withthree lugs 174, 175 and 176, the first and third of which projectforwardly whilethe second projects rearwardly througha recess 177 inframe plate 13 and is adapted to be moved into and out of the path ofmovement of pin 102., Lug 176 has a beveled edge 178 and is adaptedto bemoved into and out.

of engagement with the teeth and the end of rack163 of lever 161. Lug174 projects into the path of movement of lever 151 and is adapted to beengaged by the lower' edge thereof. Due to its weighted end, the lever171 is normally gravity actuated so that there is always a tendency onthe part of this lever to project its other end upwardly for engagementwith the teeth of the rack 163 or the lever 151, when not positivelyactuated in the opposite direction. 1

A fourth lever 183 pivoted at 184 on the frame plate 13 and s acedtherefrom is of bell crank formation aving its longer arm 185 extendingdownwardlv and its shorter arm 186 extending laterally adjacent andabove the cannon pinion assembly, the latter arm being in constantengagement with an eccentric cam 187 on the cannon pinion assembly. (SeeFigure 4). Due .tothe positioning oft-his arm, it is constantly gravityactuated downwardly, so that the longerarm 185 may be moved into and outof a position overlying the slot 188 in the frame plate 13.

The cannon pinion assembly comprises a minute hand shaft 191 projectingforwardly through the frame plate 13 and supporting a minute hand 192 atits outerend, any conventional hour hand gearing operatively connectingthis minute hand shaft with the hour band 193 (see Figure 4). Asillustrative of this gearing, a pinion 194 on the minute hand shaftdrives a gear 195 which, through pinion 196, drives a large gear 197mounted on a sleeve 198. The stepped cam 182 is provided on the cannonpinion assembly and rotates in the plane of the finger 164, thus beingpositioned forwardly of and rotating with the gear 197. A drop-off cam199 is positioned adjacent and behind the cam 187. The cam 199 isprovided with two cam shoulders and is of the type which operates itsfollower, in the instant case the finger 154, throughtwo cycles ofoperation each revolution. Thus,

the lever 151 may operate through two cycles of operation for everyrevolution of the cam 199. i

The operation of the winding and striking mechanism is as follows: I

Assuming that the striking mechanism is stationary after astrikingperiod, the cam follower or finger 154 having passed overone of the highpoints and dropped to a low point of the earn 199, and the brake 73 isslightly vreleased, the motor 16 will wind the main spring throughthetrain of gears 23, 26,29

and 32, the last of these being in engagement.

with the bull gear 33 of the differential 34.

At this time, the striking mechanism is held in inoperative'condition bythe engagement of lug 175 of the lever 171'with the pin 102, thusretaining the gear 49 in stationary condition. I

' As the bull gear 33 is rotated, the pinions 36 carried thereby, impartrotary movement to the gear 44, employing the teeth of gear 47 as atrack therefor. The gear 46 moving with gear 44, rotates the gear '52,which in turn rotates the mainspring arbor 55 by coaction with the gear.54 fixed thereon. As the main spring is wound, the collar 62 threadsinto the boss 64 carrying the fork 66 of the brake arm 67 rearwardlythus applying the brake 73 to the gear 23 and slowly retarding thewinding. The deceleration of the motor 7 trains 61, 76, 78, 82, 84 andpinion 85, all driven from the teeth 61 of the main spring cover plate59.

Assumingnow that the minute hand 192 hasjust passed the three-quarterhour mark and is in the position shown in Figure 1, the cam follower orfinger 154 is at this time resting on one of the high points of the cam199, and

in reaching this position has released lever,

161 by the engagement of the lower edge of lever 151 with the lug 174,thereby moving the upper end of lever 171 downwardly against the actionof the weight 173, moving the lug 176 out of the path of movement.v

of the rack 163.

The lever 161 is thus spring projected to the left by the action of theupper free end of the spring 181 in abutment with the upper edge of thelug 168 so that the end of the.

finger or lever 164 abuts one of the steps of the cam 182, in theillustrated position, the eleven oclock step. The rack is at this timeadvanced inwardly so that the proper number of teeth thereon arepresented to the pin.

105, the coaction of which will be presently described. At this time thearm or lug 156 of lever 151 is in a position in the path of movementofthe stop arm 101 (see Figure 3) thereby preventing the strikingmechanism from operating.

As the minute hand 192 reaches the hour mark, the cam follower 154 dropsoff the high point on the cam 199 and is projected upwardly by thespring 181, thus moving thelug 156 out of the path of movement of theferential is free to operate so that the gear j5unde the expansioninfluence of the main spring is rotated in a d rection reversed fromthat in winding and transmits rotative energy to the gear 52 which inturn rotates gear 4,6 (see'Figure 2).

The hull gear 33, which is prevented from reverse rotation by the dog107, now rema ns stationary so that the differential pinion pivotsremain stationary. With the. pinions 36 thus permitted to rotate aboutstationary pivots, the gear 44 moves in-a clockwise direction asseen. inFigure 2 with its companion gear 16 and through the differentialpinions, rotates the companion gears 47 and 419 in a counter-clockwisedirection as viewed in Figure 3. The pins. 51 each in turn engage theupper edge of the arm causing both hammers of the striking means to beraised as each pin reaches its lOWS11F 30S1131011,.tl16 hammers and 126being permitted to fall suddenly bythe disengagement or release ofthearm 124 from the pin.

During the strlkingoperation, the gear 19 through pinion 91 rotatesarbor 92 in a clockwise :directiomthus rotating the pin 105 on the headportion 104 'which atthe top of its path of movementi engages the teethof the rack 163. As the rack 163 is .movodto the right, the beveled edge178 of .thc-lug 1' 6 is engaged by eaclrsuccessive tooth of the rack,and end of lever 17]: being cammed downwardly in passing, and dogg ngthe rackagainst return movement after 4 1 Mr. 1 i. 1'-r J1 each tronRik- 3b by the rug in). he reslationship between each striking impulsetransmitted tothe hammers by each pin 51 1S suclras to account for onecomplete revolution of thearbor 92, and consequently pin 105,

which in turn upon each revolution moves the rack 163 one tooth to theright, each tooth -.acconnting for one strike andthus controlling thenumber of, strikesto'be -ma'de by both hammers in unison.

hen the lug 17 6 has passed the end tooth 179-of the rack, theweight173- acts to raise heater governor '99 by its engagement with pinion 97on its arbor'98, so that the governor controlsthe speed and smoothnessof operation of the striking mechanism.

1 are struck on the hour, while only one gong The control part-s are nowin a posit-ion preventing the operation of the striking mechanism untilthe next striking interval is reached.

As the minute hand approaches the quartor-hour point, cam follower orfinger 154 is again depressed against the pressure of spring 181, butthe high point or cam199 effective at this time is not quite as high asthe one efi'ective prior to the hour interval, so that lever 151 is notmoved outwardly as 'far as prior to the hour interval. Hence lever 171is not cammed downwardly by the engagement of the lower edge of lever151 with lug 17 1, whereby lever 161 is not released for J swingingmovement to the left (see Figure 1). Lever 151 is, howev r, movedsufficiently to the right to cause the lug to move out of the path ofmovement of pin 102 and. to place the lug 156 in the path of movement 7'of arm 101, (see Figure Thus gear 93 will rotate slightly until arm 101engages lug 156. At this time, cam 187 on the cannon pinionasscmbly willhave permittedarm the striking mechanism. This operation is,

however, limited to one revolution of gear 93 due to the prompt raisingof lug 178 by the action of weight 17 3 of lever 171 into the path ofthe end 179 of the rack 103 of lever 161, thereby permitting lug 175 topromptly assume its position in the path of movement of pin 102. Thisrotational movement of gear 93 is only sullicient to permit one pin 51to ride over the edge of arm 124. Since arm 121 is at this time inelevated-position, and arm 185 will permit but-a slight movement of lug139 in the arcuate slot 188, only arm 122 and its hammer 126 will drop,resulting in a sounding of only gong 11. The succeeding pin 51 of gear49 will only engage arm 124 su'lficiently as the striking mechanism isbrought to rest to slightly raise both arms 1'21 and 122.

It will thus be apparent that two gongs giving a distinct harmonizingaudible signal is struck on the half-hour.

As the minute hand proceeds in its movement around to the threequarterhour point, the control parts remain in the same position as they assumefollowing an hour striking period hereinbefore described.

\Vhen the minute hand again reaches'the three-quarter hour point, thecam fol-lower or finger 154 is again depressed against the pressure ofspring 181 moving the lug 175 out of the path of stop pin 102, lug 156intothe' path of stop arm 101, and the lug 176 out of the path of therack 163, whereby rotation of the hour hand.

Hence in the next operation of the'strikin 'mechanism at the end of thehour period, the crack member 163 will have to be moved outwardlythrough the space of one more tooth before the lug 176 can swingupwardly in advance ofthe tooth 179, resulting in one more strikingimpulse being given the'hammer 126, at the next strikingoperation. Thisextra impulse will be added to each successive hour striking operationfrom one oclock to twelve oclock, owing to the finger 164 movinginwardly to a greater degree in contacting with the successively lowerstep of the cam 182 at successive striking intervals.

It will be evident from the foregoing that theclock mechanism andstriking mechanism both derive their operating energies from a singleconstantly energized electric motor so that the operation of the clockcontinues indefinitely without manual winding of any spring. Thecontinuously acting torque of the motor effective on the main spring ofthe clock movement at all times excepting during a striking period,results in the tension of this clock spring being maintained betweenvery close limits, approximating a uniform tension on the spring at alltimes. It will be apparent that this augments the time keeping accuracyof the clock. 'When the main spring tension is such that the s ring isin fully wound condition, the forke end 66 of the brake lever 67 willhave been moved rearwardly by the rearward movement of the collar 62 andits flange 65 impinging upon the fork 66 as the collar threads into itsthreaded. boss, thus applying the brake 73 by the transmission ofrearward pressure to the brake shoe 75 which will inturn frictionallyimping upon the gear 23, thereby stalling the motor.

The motor will remain in stalled condition until the brake 73 will havebeen moved forwardly slightly by the unwinding of the main spring, thusrelieving the pressure on the gear 23, when the constantly energizedmotor will again energize the gear train to the differential.

Since the tension of the main spring is maintained between very closelimits, it will be evident that the motor will energize the gear trainto the differential at very short intervals. In view of this condition,it will be further apparent that the motor will be active duringpractically every striking period. While I have hereinbefore describedthe operation of each gear train, namely (1) from the motor to the mainspring through the differential and (2) from the main spring to thestriking mechanism, it will be understood, that while a condition mayarise when each train may operate independently of the other, due forexample to a failure of the current in the line, an instant or so priorto the striking period and a resumption of the line current shortlyafter the expiration of a striking period, that generally in the normaloperation of the device, owing to the frequency of the intermittentbrake release, and

the consequent energization of the gear train from the motor to thedifferential as hereinbefore explained, the striking operation willoccur concurrently with the energization of the gear train from themotor to the differential.

During this concurrent operation, all the energy transmitted from themotor to the differential is taken up by the striking mech-' anisms dueto the fact that the relative arrangement of the gear trains from themain spring to the differential and from the motor to the differentialis such that even though the motor is operating, the main spring willstill unwind slightly during a striking period. As viewed in Figures 2and 3, during this operation, the bull gear 33 is rotated in acounter-clockwise direction. The relative movements of the various partsof the differential are such that with the bull gear turning in acounter-clockwise direction, the slight, movement of the gear 44 inaclockwise direction due to the slight unwinding of the main springpermits the teeth of the gear 44 to act as a track for the pinions 36 sothat the gear 49 rotates in a counter-clockwise direction. Upon suchrotation of the gear 49, the pins carried thereby will operate the hourstriking hammer through the coaction therewith of the arm 127.

It is to be noted, that since the energy transmitted bythe motor duringa striking period is entirely exhausted by the striking mechanism andthat since the main spring is unwinding during the striking period, assoon as the striking mechanism ceases to operate by virtue of thestopping thereof by the auto- 'matic operation of the control means, theenergy transmitted subsequently to the difthe motor'will be installed bythe applica-'.

ti on of the brake 73 upon the gear 23. v

If it is desired to render the striking mechanism inoperative, the stoparm 114 may be rotated to the position indicated in dotted lines inFigure 3, when the lug 115 will lie 'strikingmechanism and clockworks'in the path of movement oi-tlie pins iii :2 upon engagement thereof, the'prevented ifrom:rotation.

Itwill he evident from the foregoin 'that shou'hl the line currentfailduring a st ming period thereby dcenergI 'n unotor,'the -mziinspring will nevertneless carryover the operation of" -king mechanism,thus inthe suring a completion of the striking periodregardlessofthezfailuroof the line current.

It is tohennderstood that the term strile ing mechanism is :not limitedto devices striking agong, or toithat part Oi the meclnn nism whichoperates upon an instrumcnt-ality acting as the scurcoofan an'dihlesignal, for

example such as athe hanim er, but i is intended toembrace all forms ofa))aratus-desi netl -to audibly or otherwise indicate predetermined time"periods in the operation of "clock.

Sofar as I'am eware,hltam.the first-in -the art to provide a strikingclock Where-indie are both actuated'bvthe main springtand wherein asingle constantly energized riiiotoi operates the striking 'mechamsmduring a striking period and is adapted to wind the main springbetweenstriking periods.

The novelarrangementrof gears and the =interposition of thedifi'eient-ialxand the coaction'the-rewith of the main spring oftheclockby the slight unwinding of the latter during a striking'period,renders'the single motor sufficient for purposesof operating both theclock'mechanlsm and the striking mechanism.

lVhile I have shown what I regard as a preterred embodiment of myinvention, it 'will he understood that modifications and rearrangementsmay he made therein by those skilled inlthe art without departing fromthe spirit and scopoof the appended "claims or the essence of theinvention.

lVhatI claim: as my'invention and desire to secure by Letters Patent is:

1. In combination, a clock movement, a main spring, connectionsbetweenthe two for operating the 'formerby the latter, a

striking mechanism, means for controlling the striking mechanism, a.constantlyenergized electric motor, agear train connecting the motorWiththe main spring'for effecting Winding of'the springby the motor,adif- 'iferential in said train, and means'on 'sa-id differential foroperating said striking 'mechanism, the diiierential transmitting all ofthe energy ot' the motor andaportion of the energy of the main spring tothe striking mechanism during a striking period for operating saidmechanism, "should the motor fail, the differential transmitting energyfrom the main springto'the striking mech anism for operation thereofduring a striking period, and should the main spring be unwound thedifferential transmitting en- 'ergy zfrom the motor to the strikingmechanism for operating sameduring a striking period.

2. In combination, 'a clock movement, a main spring,connections betweensaid movement and main spring for actuating the foriner by the latter, astriking mechanism, a governor, s constantly energized electric HtOl,-9.gear train between the motor and C said main spring for eiiectmg wmdmgot" the springbythe motor, a diiferentia'l in said train, and a secondgear train connecting said differential with said governor means :on thedifferential for reflecting operation of said striking mechanism duringa striking period by the motor and the main spring underthe control ofsaid-governor, the main :epring being wound by the motor through thedifferential between striking :perio( s,

said gear trains and differential permitting the main spring to operatethe strikin 'mechanism during a striking period SllOlllt the motor tail,and control means for the unotor controlled byzt-he main'spring to stopsaid motor when the main spring is fully Wound.

3. In combination, a clock mechanism :havinga mam spring; a strikingmechanism,

means :for controlling :the .=str1king meoha-fl.

nism, a'eonstantlyenergized electric motor.

a ditferential'having albu'llsgear, 'anda spur gear oneach-side of thebull gear, .a gear it-rain connecting saidmotor with saidbull gear, agear train connecting said -main spring w'ithone of the spur gears, and.e gear train eonnecting said striking mechanism 1 control means :withthe other of said spur-gears, to ennble theimotor and the main springconjointly -to o crate the strikingii In witness whereof, Ihereuntosubscribe myname this 10th day of.April,-.1930.

ROSCOE H. VILMETH.

